The Simplified Psoriasis Index (SPI): A Practical Tool for Assessing Psoriasis

Abstract

The Simplified Psoriasis Index (SPI) is a summary measure of psoriasis with separate components for current severity (SPI-s), psychosocial impact (SPI-p), and past history and interventions (SPI-i). It derives from the Salford Psoriasis Index but replaces Psoriasis Area and Severity Index (PASI) with a composite weighted severity score designed to reflect the impact of psoriasis affecting functionally or psychosocially important body sites. Two complementary versions are available, differing only in that current severity (SPI-s) is either professionally (proSPI-s) or patient self-assessed (saSPI-s). This study examined the criterion and construct validity and response distribution of proSPI-s, saSPI-s, and SPI-p in 100 patients with plaque psoriasis. A further 50 patients were assessed for test-retest reliability of these three components. Interrater reliability of proSPI-s was assessed in 12 patients, each assessed by 12 assessors (144 assessments). There was close correlation between PASI and proSPI-s (r=0.91); SPI-p was closely correlated with the Dermatology Life Quality Index (r=0.89). Strong intrarater (proSPI-s, saSPI-s, SPI-p, and SPI-i) and interrater (proSPI-s) reliability was demonstrated (all intraclass correlation coefficients >0.75). There were wide response distributions for all three components. We believe that both professional (proSPI) and self-assessed (saSPI) versions can readily be introduced into routine clinical practice.

Assessing Psoriasis Severity and Outcomes for Clinical Trials and Routine Clinical Practice

“…6). 22,23 It was shown to correlate more closely with DLQI (r 5 0.82) and the psychosocial impact score of SPI (SPI-p; r 5 0.78) than did either proSPI-s (r 5 0.59) or PASI (r 5 0.60), suggesting that it better reflected the patients' own perceptions of their disease severity than did the observer-rated scores. 20 There was nevertheless good correlation between the saSPI-s and both the PASI (r 5 0.70) and the proSPI-s (r 5 0.70).…”

“…More recently the selfassessment Simplified Psoriasis Index (saSPI) has been proposed for patient self-reporting of psoriasis severity. 22,23 It has been recognized for at least 70 years that there is an intimate relationship between psoriasis and psychological distress. [24][25][26] It has now become standard practice to include some measure of psychosocial impact in clinical trials of interventions for psoriasis.…”

“…Simplified Psoriasis Index (SPI) 22 is a composite summary measure of psoriasis with separate components for current severity (SPI-s), psychosocial impact (SPI-p), and past history and interventions (SPI-i). It is available in 2 complementary versions, one for completion by health care professionals including dermatologists, dermatology nurses, and primary care physicians (proSPI) and a self-assessment version for completion by the patient (saSPI).…”

Detection of small changes of psoriasis intensity with the PrecisePASI

“…from 1% increasing to 9% which are both graded as area involvement of '1', the PASI remains unchanged due to its calculation. In addition, the reproducibility of PASI has been criticized repeatedly [2][3][4][5] due to inter-observer variation, overestimation of the involved areas by untrained observers [6,7] as well as its non-linear scale and lack of sensitivity at the lower end of its range [4] .…”

Detection of Small Changes in Psoriasis Intensity with PrecisePASI

“…In addition, the reproducibility of PASI has been criticized repeatedly [2,3,4,5] due to inter-observer variation, overestimation of the involved areas by untrained observers [6,7] as well as its non-linear scale and lack of sensitivity at the lower end of its range [4]. …”